232 



ANIMAL PHYSIOLOGY. 



[LESSON 69. 



FIG. 



fibre consists in certain nodosities (bullae), developed at certain inter- 

 vals, and these are found to contain a nucleus. 



1036. To render this latter fact apparent, it is 

 frequently desirable to employ acetic acid, but prep- 

 arations are not uncommon which have not been 

 subjected to the action of any re-agent, but in which 

 the nuclei are well seen. A figure of the non-striped 

 fibre is given (Fig. 360). 



1037. The true structure of muscular fibre, as 

 revealed by the microscope, was first published in 

 the Philosophical Transactions, by Mr. William 

 Bowman, and that account has been made available, 

 in addition to original observations and preparations. 



Non-striped mus- 

 cular fibres. 



LESSON LXIX. 



COMPOUND TUBULAR TISSUES, CONTINUED. NERVOUS SYSTEM. 



1038. The late Baron Cuvier applied himself to correct the 

 errors in the classification of Animals which had been handed down 

 to us by Aristotle, the Father of Natural History, altered, but not 

 improved, by Linnaeus, and descended to our own times. 



1039. To this end he devoted much time and untiring labor to 

 the dissection of the nervous systems, especially of the Invertebrate 

 animals. The result of these labors was, the division of the entire 

 animal kingdom into four primary divisions, or sub-kingdoms. 



1040. Notwithstanding that the structure of the nervous system 

 really formed the basis of his classification, he contented himself with 

 the prominent external characters, as the means of designation of 

 his three lower classes, and only in the first class is an internal 

 character adopted. 



1041. Thus the animal kingdom consisted, according to this 

 author, of the following divisions : 



VERTEBRATA, . ARTICULATA, 



MOLLUSCA, RADIATA. 



1042. All the animals of the first class possess a bony vertebral 

 column, for the transmission and protection of the spinal chord. 



1043. The MOLLUSCOUS animals were so called from the general 

 softness of their bodies, such as slugs, snails (marine, fresh-water, 

 and terrestrial), the inhabitants of bivalve (bis, two) and univalve 



